The present invention relates to scanning probe microscopy, and in particular to the construction of a combination scanning probe and optical microscope for use in atomic force microscopy.
High quality optical views of a sample under investigation by a scanning probe microscope maybe obtained by combining the scanning probe microscope with an optical microscope. The optical view may be used, for example, to view gross features on the sample and track the position of the scanning probe with respect to the gross features. In this manner, the scanning probe may be conveniently maneuvered to particular areas of interest on the sample. The optical view may also be used to monitor processes optically as the scanning probe touches or manipulates molecules on the sample. A variety of combined scanning probe and optical microscope arrangements have been proposed. However, the presence of the optical microscope assembly tends to degrade the scanning probe performance because the optical microscope assemblies used tend to be relatively massive and, as such, tend to transfer significant low frequency resonant vibrational frequencies to the sample stage. As a result, the sample stage undergoes significant vibrational displacement, directly degrading the scanning probe analysis. Accordingly, there remains a need in the art for a combined scanning probe and optical microscope which is less prone to low frequency vibration than the designs of the prior art.
Another challenge associated with the design and operation of combined scanning probe and optical microscopes is presented in the context of magnetically induced oscillation of the scanning probe. Solenoids are commonly used in this art to induce oscillation in the scanning probe. Locating the solenoid for optimum probe displacement and control has traditionally been problematic. Accordingly, there exists a further need in the art for a scanning probe microscope design where a solenoid may be arranged in an optimum configuration.
Still another challenge associated with the design and operation of combined scanning probe and optical microscopes is presented in the context of sample placement, removal, and replacement. Typically, where an optical microscope is combined with a scanning probe microscope, the resulting design is cumbersome in that it is difficult to place, remove, and replace samples. Accordingly, there exists a further need in the art for a scanning probe microscope design that provides for convenient sample placement, removal, and replacement.
These needs are met by the present invention wherein, in accordance with one embodiment of the present invention, a combined scanning probe and optical microscope is provided. The microscope comprises a sample stage, a scanning probe microscope, an optical microscope, a microscope coupling, and a sample stage support. The sample stage defines an upper surface and a lower surface. The scanning probe microscope is configured to examine a surface of a sample supported by the upper surface of the sample stage from above the sample stage. The optical microscope is configured to examine a sample supported by the upper surface of the sample stage from below the sample stage. The microscope coupling mechanically couples elements of the scanning probe microscope to elements of the optical microscope. The sample stage support is configured to isolate the sample stage from the optical microscope. The sample stage, the scanning probe microscope, and the sample stage support define relatively high frequency mechanical resonances. The optical microscope defines relatively low frequency mechanical resonances. The microscope coupling, the sample stage, and the sample stage support are arranged to inhibit differential motion between the sample stage and the scanning probe microscope in the event of low frequency vibrations in the optical microscope.
The combined scanning probe and optical microscope is preferably designed such that a critical path coupling low frequency vibrations generated in the optical microscope to a sample supported by the sample stage runs from the optical microscope, through the microscope coupling, the sample stage support, and, finally, the sample stage. The sample stage support and the sample stage are preferably designed such that the critical path is not conducive to low frequency vibrational coupling. The scanning probe microscope, the optical microscope, and the microscope coupling may define a microscope chassis and the sample stage support may be configured to function as the sole significant source of vibro-mechanical coupling between the sample stage and the microscope chassis.
In accordance with another embodiment of the present invention, a scanning probe microscope is provided comprising a sample stage, a scanning probe microscope, a microscope coupling, a sample stage support, and a slide-mounted stage assembly supported by a microscope chassis. The scanning probe microscope is configured to examine a surface of the sample. The microscope coupling supports elements of the scanning probe microscope. The sample stage support is configured to suspend the sample stage from the microscope coupling. The slide-mounted stage assembly is arranged to permit slidable movement of the sample stage and the sample stage support relative to the microscope chassis.
In accordance with yet another embodiment of the present invention, a scanning probe microscope is provided comprising a sample stage, a scanning probe microscope configured to examine a surface of a sample supported by the sample stage, a microscope coupling, and a sample stage support configured to suspend the sample stage from the microscope coupling. The scanning probe microscope includes a solenoid driven cantilever assembly comprising a cantilever unit, a probe tip, and a solenoid unit. The cantilever unit is positioned above the sample stage and comprises a flexible cantilever having a free end and a confined end. The probe tip is defined at the free end of the flexible cantilever. A solenoid unit is positioned above the cantilever unit and comprises a magnetic core and a solenoid winding. The solenoid unit is configured to cause movement of the free end of the flexible cantilever.
In accordance with yet another embodiment of the present invention, a solenoid driven cantilever assembly is provided comprising a cantilever unit, a probe tip, and a solenoid unit. The cantilever unit comprises a flexible cantilever having a free end and a confined end. The probe tip is defined at the free end of the flexible cantilever and defines an apex on a lower side of the cantilever unit. A solenoid unit is positioned above the cantilever unit and comprises a magnetic core and a solenoid winding. The solenoid unit is configured to cause movement of the free end of the flexible cantilever.
Accordingly, it is an object of the present invention to provide a combined scanning probe and optical microscope which is less prone to low frequency vibration than the designs of the prior art, a scanning probe microscope design where a solenoid may be arranged in an optimum configuration, and a scanning probe microscope design that provides for convenient sample placement, removal, and replacement. Other objects of the present invention will be apparent in light of the description of the invention embodied herein.